Two cases of multinodular and vacuolating neuronal tumour

An unusual multinodular and vacuolating neuronal tumour (MVNT) has been described in the cerebral hemispheres of ten patients with adult-onset seizures. We report the findings in two cases with similar features, a surgical resection and the other an autopsy specimen. Case 1, a 34-year-old female, underwent surgical resection for a multinodular non-enhancing frontal white matter lesion causing intractable epilepsy. Case 2, presented with motor neurone disease (MND) at the age of 71 and MRI scanning revealed extensive multinodular non-enhancing white matter lesions in the temporal lobe. There was no history of epilepsy and post mortem histology confirmed MND. Macroscopically multiple small grey well-formed, discrete and coalescent nodules were seen in the deep cortex and subcortical white matter. On histology, mature-looking neurons with large cytoplasmic vacuoles were distributed in a fibrillary background, where vacuoles were also noted. In the resected tumour scattered oligodendroglia-like cells were present. No ganglion cells were seen. The vacuolated cells exhibited immunopositivity for synaptophysin, HuC/HuD and p62 but were negative for NeuN, neurofilament, GFAP, IDH1, nestin and CD34. Electron microscopy showed non-membrane bound cytoplasmic vacuoles in the neurons and in some neuronal processes. The seizures recurred in Case 1. Some clinicopathological features of this lesion suggest a possible relationship with dysembryoplastic neuroepithelial tumour (DNT) although the morphological features are not typical of DNT. Case 2 demonstrates that MVNT may remain asymptomatic.